For many years, varius types of binders have been available commercially for use in binding a sheaf of papers or like sheets together as reports, as sample colelctions, as file groups, and for other like purposes. Likewise, for many years, file folders have been avilable with suspension elements which extend beyond the upper edges of the folders and on which the folders may be supported by a pair of spaced rails to permit their use in a suspension type filing system.
While there is a substantial area of overlap between binders and file folders in terms of their use, they are not interchangeable. Binders are not readily integrated into the usual suspension type file system, and instead are normally stacked or shelved separately. And file folders having fixed suspension elements generally are not circulated with their contents because of the danger that such elements will snag, scratch or damage other objects. Obviously, therefore, a combination unit capable of providing the features and advantages of both a binder and a suspension type file folder would be quite advantageous.
Hereinafter, for purposes of convenience the unmodified term "folders" will be understood to refer to file folders which have suspension elements, whether fixed or retractable, and which are intended for use in suspension type file system.
On a number of occasions in the past, others in the art have recognized the desirability of hybridizing binders and folders to provide binders suitable for use directly in suspension type file systems, thus eliminating the need for storing the binders separately or using separate folders for holding either the filled binders or the unbound material from the binders.
For example, U.S. Pat. No. 4,114,963 illustrates a folder adapted for use somewhat like a binder. This patent discloses a suspension folder having permanently but slidably mounted over the upper outer edge of each of its two leaves a channel or "U" shaped suspension element. These four elements normally are extended to support the folder in a suspension type file, but are retractable should the user wish to remove the folder from the file and use it as a cover for protecting its contents while they are in use in the course of normal office work.
Other patents suggest the opposite approach--that of adapting report binders for use in suspension type file systems. U.S. Pat. Nos. 3,572,867, 3,957, 321 and 4,487,520 are illustrative of one general type of structure involving this approach. This structure includes use of a pair of cover/flap units, with the flaps being pressed over the marginal edge of a sheaf of papers by a compression assembly including a compressor bar carrying two suspension hooks which are slidable on the bar between retracted and extended positions.
U.S. Pat. No. 4,288,170 discloses a similar structure, except that it proposes a double set of compressor bars and retractable extension members. And U.S. Pat. No. 3,865,445 discloses a complex suspension assembly including movable and fixed parts which permit use of the binder with various types of filing systems.
Other approaches to a combination unit are suggested in U.S. Pat. Nos. 3,801,175 and 4,208,146. In U.S. Pat. No. 3,801,175 a pair of retractable hanger units of substantial width are slidably mounted in groves at the edges of a relatively wide spine. In U.S. Pat. No. 4,208,146, a ring type notebook is adapted for suspension filing by an assembly which is loosely carried on the ring binders along with the papers and which provides a pair of relatively wide retractable hangers.
Although the above discussed prior art clearly indicates that the need for a hydridized binder/folder has long been recognized, none of the structures suggested to date are believed to have met with any significant commerical success. They have either been too costly to implement, too cumbersom or complex to assemble or use, or too consuming of available file space. For example, aside from any other disadvantages they might present, the thickness of the four channel members of U.S. Pat. No. 4,114,963, the large cumbersome suspension unit of U.S. Pat. No. 3,865,445 or the added thickness of the dual set of hangers of U.S. Pat. No. 3,957,321 would render these and similar structures unsuitable for use simply because of the space they would consume in a filing system.